I would second (or third or fourth) those who say do nothing with it. We sold my IL's house last year - much more expensive area of the country but otherwise pretty similar situation in terms of the state of the house. They were smokers in the house for 40 years so you can imagine the state of the walls, carpets, cupboards, doors - everything. The decor was also dated and it needed new bathrooms and kitchens. All three estate agents advised doing NOTHING with the house. The advice was that the amount of money which needed spending would result only in a corresponding increase in the sale price i.e. spend £50k and we would get an extra £50k on the sale price. However, the time taken to do all these works (either ourselves which was completely unthinkable) or getting contractors to do it (which still required significant input of time in terms of managing, choosing cupboards, tiles etc) meant a considerably delayed sale and remaining responsible for the house, insurance, garden maintenance etc. with no increased profit at the end.
Importantly, they also said that most likely the electrics and heating would need replacing which is a major expense. If you can get away with not doing this work, there is no point in decorating anyway because new buyers come in, look at the ancient radiators and realise that they will damage the new paintwork and have to lift the flooring in order to replace them anyway. The agents said the only way to increase the profit on the house was to go beyond a renovation for sale by e.g. by building on an extension in which case we might increase the sale price beyond the amount spent.
They also said that by renovating we were actually limiting the pool of buyers because while people might like a fresh, new house they might equally not like the kitchen installed or the flooring chosen. Not everyone wants an inoffensive white kitchen or beige carpets but if factored into the sale price, neither can they then afford to change it! By selling in an unrenovated state, it also appeals to people who want to live in the area but can't generally afford it. However, if they can get a house which needs lots of work, they can do the minimum to move in and then gradually do the rest over a period of years.